topology: Fix compilation warning when not in SMP

The topology_##name() macro does not use its argument when CONFIG_SMP is not
set, as it ultimately calls the cpu_data() macro.

So we avoid maintaining a possibly unused `cpu' variable, to avoid the
following compilation warning:

drivers/base/topology.c: In function ‘show_physical_package_id’:
drivers/base/topology.c:103:118: warning: unused variable ‘cpu’ [-Wunused-variable]
define_id_show_func(physical_package_id);

drivers/base/topology.c: In function ‘show_core_id’:
drivers/base/topology.c:106:106: warning: unused variable ‘cpu’ [-Wunused-variable]
define_id_show_func(core_id);

This can be seen with e.g. x86 defconfig and CONFIG_SMP not set.

Signed-off-by: Vincent Stehlé <[e-mail]>
Cc: Greg Kroah-Hartman <[e-mail]>
Cc: <[e-mail]> # 3.10.x
Cc: <[e-mail]> # 3.13.x
Cc: <[e-mail]> # 3.14.x
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/base/topology.c

···
 static ssize_t show_##name(struct device *dev,			\
 		struct device_attribute *attr, char *buf)	\
 {								\
-	unsigned int cpu = dev->id;				\
-	return sprintf(buf, "%d\n", topology_##name(cpu));	\
+	return sprintf(buf, "%d\n", topology_##name(dev->id));	\
 }
 
 #if defined(topology_thread_cpumask) || defined(topology_core_cpumask) || \